Firearms examiner Marshall Robinson retrieves a shell casing from the bullet recovery tank at the Bridgeport Police Firearms Lab on Thursday, August 16, 2012. Bullets are fired into the tank, which is full of water, and then examined in the effort to tie a firearm to a particular crime. less

Firearms examiner Marshall Robinson retrieves a shell casing from the bullet recovery tank at the Bridgeport Police Firearms Lab on Thursday, August 16, 2012. Bullets are fired into the tank, which is full of ... more

Firearms examiner Marshall Robinson fires a recovered handgun into a bullet recovery tank at the Bridgeport Police Firearms Lab on Thursday, August 16, 2012. The cardboard around the tank opening keeps shell casings contained. less

Firearms examiner Marshall Robinson fires a recovered handgun into a bullet recovery tank at the Bridgeport Police Firearms Lab on Thursday, August 16, 2012. The cardboard around the tank opening keeps shell ... more

Five days a week his eyes stare through the double-eyepiece Leica comparison microscope at his desk. They move only to check the screen on the Dell laptop computer to his right, the enormous magnifying glass to his left or the pages in one of the numerous photo albums shelved above him.

And they search strenuously -- for comparable indentations, scratches or marks on bullets, cartridge casings and inside guns.

A perfect match could send a shooter to prison.

Failure means more work for detectives.

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Brian Pounds took photos on Aug. 23

Tasked with reviewing evidence from nearly 200 shooting cases every year and five homicides in the past month, Robinson doesn't suffer for lack of work. The 73-year-old nationally known ballistics expert now is working for Bridgeport and the State Police.

"I love what I'm doing," says Robinson, whose grandfatherly appearance portrays the image of someone you'd expect to see frolicking in the park with grandkids rather than straining his eyes matching miniscule marks.

"The only way I'll leave is when they wheel me out of here," he quips.

`UNMATCHED ANYWHERE'

He has been at this work since 1972. That's when the State Police advertised for a second firearm examiner. Robinson, already a trooper, always had a keen interest and strong knowledge of guns. He got the job, retired in 1985, but continues to work as a consultant.

"Due to the speed and heat from the bullet traveling down the barrel, its copper jacket was plating the barrel," he says. "Every test-fired bullet had different markings because it was pushing the old plating off and laying new plating down the barrel."

Another test 14 years earlier was more successful.

That time Robinson reviewed the bullets that provided the evidence sending Nicola Sacco and Bartolomeo Vanzetti to the electric chair for killing a payroll guard in 1920.

On Mondays and Thursday, Robinson's work as the ballistics expert for the Bridgeport Police Department is less high-profile -- checking spent shell casings found at crime scenes, inspecting bullets pulled from bodies and test firing seized guns.

"We are very lucky to have a person like Marshall Robinson working with us to solve crimes and catch violent criminals," says Bridgeport Police Chief Joseph Gaudett. He has a depth and breadth of knowledge and abilities unmatched anywhere in the state."

On the weekdays he's not in Bridgeport, Robinson works at the State Police Forensics Lab in Meriden.

The work is the same at both places. Slow, meticulous and voluminous.

He spends hours trying to match bullets or casings with hundreds others he previously examined. The reality is matches are few.

A PAINSTAKING PROCESS

On this day, Robinson is examining a bullet pulled from a Bridgeport shooting victim's skull and the casing found at the scene. The hope is to link them to other shootings.

Using tweezers, Robinson carefully opens a vial and extracts the once-rounded bullet that now resembles a snail's shell. It was reshaped by the skull bones it shattered.

"I've seen much worse," he said. "As long as I have part of the outer surface that came in contact with the barrel, I can work with it."

Robinson drops the bullet into an ultrasonic tank holding a 50-50 solution of water and bleach.

"That'll kill anything on it," he said. "I won't have to wear gloves."

After a minute or so Robinson removes the bullet, weighs it and begins studying.

"It's a .25-caliber with a full metal jacket," he immediately said. He scratches his initials along with the case and evidence numbers into it and takes a close-up photo.

"That's for the evidence file," he explains.

He then places the bullet under his comparison Leica microscope with its double eyepiece.

"I'm looking for grooves and lands, the area between the two grooves," he explains. "I'm also looking for directional twists," which are created as the bullets travels through the barrel.

But, Robinson acknowledges, all this is of little use unless he has the suspected gun. Then he could test fire it with a new bullet and compare the markings.

No gun was recovered in this case.

So he takes the information assembled on the bullet, slides over to another computer and enters it onto an FBI form. That program spits out 110 guns that could have fired that bullet. He prints out the report and attaches it to the file.

"Maybe someday we'll get lucky and find one," he says.

The spent casing holds more interest.

"Most guns will leave their own individual marks on the cartridge case," he explains. "No two guns leave the same marks, even if they are the same model."

The bullet's caliber tells him where to begin looking.

A firing pin mark can be found near the perimeter of a .25-caliber bullet's rim. A .22 will have the mark on the rim.

"It'll stay in that system now," he explains. "It'll be compared against future casings."

MAKING A MATCH

On another day, he's looking at two .25- caliber casings found at a crime scene a year apart. Again the casings are lined up under his stereo microscope.

While gazing at the markings through the microscope, a burly state police trooper enters with a tightly taped evidence box. He asks Robinson to take a look at the seized gun inside and give him a report.

"Come back around 11," the expert said. "I want to finish this up first."

Robinson then returns to the casings. He matches the markings against one found in his photo library. Slowly he rotates one of the images against the second. It's almost as if he were working a one-sided Rubik's cube. The casing turns and turns and turns until it lines up perfectly.

"See that," he said triumphantly. "These were fired from the same gun -- a year apart. The report will go to the detective handling the investigation."

Robinson now opens the evidence box and looks at the gun seized by the state police.

"This is a Herters .44 magnum made by J.P. Sauer and Sons in Germany," he said. "This is not a typical gun used in crimes."

Still, Robinson copies down the serial number, measures the barrel, checks for firing residue and even test fires a bullet into his nearby water tank.

Photographs are taken, a report is done and the gun is returned to the evidence case.

"I have this if I need it," he said. "But it's highly unlikely I'm ever going to need it."